Here is Jerry Bridges from
The Discipline of Grace (p.78,79) on our tendency towards legalism and self-righteousness as we are seeking to follow Jesus:
"When I was first introduced to the idea of Christian discipleship, I was given a list of seven spiritual disciplines I should practice every day - things such as a daily quiet time, Bible study, Scripture memorization, and prayer. All of those disciplines were very helpful to me, and I am grateful for every one of them. They formed the foundation for my spiritual growth. However, while learning those disciplines I came to believe that my day-to-day relationship with God depended on how faithfully I performed them. No one actually told me that God's approval of me was based on my performance. Still, I developed a vague but real impression that God's smile or frown depended on whether or not I did my spiritual exercises. The challenge to be faithful in my quiet time, while good in itself, probably contributed to this impression."